Experimental Study And Engineering Practice Of Seismic Behavior Of Rammed Earth Wall Constrained By Ring-beam Construction Columns

Rammed earth has a distinct architectural style,with the advantages of energy saving,environmental protection,low cost,regulating moisture and ventilation,adjusting measures to local conditions and so on,so it is widely used in the rural areas of western China.However,due to the poor mechanical properties of rammed earth materials,and the traditional rammed earth dwellings are mostly built by farmers,the construction process is rough,lack of basic structure and effective anti-seismic structural measures.As a result,rammed earth houses are of poor quality and lack of safety performance,and are seriously damaged in previous earthquakes.In order to overcome the defects of the above traditional rammed earth materials,the concept of modern rammed earth architecture is put forward.Modern rammed earth architecture is aimed at three aspects: traditional ramming material,ramming technology and structural design.Modern scientific and technological means are used to improve the poor mechanical performance and seismic performance of traditional rammed earth buildings.In order to study the seismic performance of modern rammed earth structure,the seismic performance of modern rammed earth wall confined by ring beam structural column is studied by quasi-static test.On this basis,through engineering practice,the seismic structure and construction technical suggestions of modern rammed earth structure are put forward.The main research contents and conclusions are as follows:(1)In order to improve the mechanical properties of rammed earth wall constrained by ring beam structural column,the proportion of wall material is optimized based on the previous research results of the research group.39 rammed earth cube specimens with different ratios were made and axial compression tests were carried out to determine the optimal mixture ratio.Rammed earth material prism compressive experiments of elastic modulus,poisson's ratio,compressive strength index,and through the direct shear test of rammed earth material Angle of internal friction and cohesion.(2)Three pieces of rammed earth walls confined by ring beam structural columns are designed and made,and one piece of rammed earth walls without structural measures is compared,and four specimens of modern rammed earth walls are tested under low cyclic load.the seismic performance parameters such as damage development,failure mechanism,hysteretic characteristics,stiffness degradation and energy dissipation of rammed earth walls constrained by ring beam structural columns are compared and analyzed.The test results show that the ring beam and the structural column form a closed "weak" frame.The "hoop" of the internal rammed earth wall can effectively restrain the deformation of the internal rammed earth wall,enhance the deformation capacity of the rammed earth wall,limit the horizontal dislocation of the rammed earth wall,and delay the collapse time of the rammed earth wall.(3)By using the modern ramming construction technology,the improved rammed earth material and the rammed earth wall restrained by ring beam and concrete filled steel tube column with better deformation and bearing capacity in the test results are applied to the practical engineering of modern rammed earth construction.The structural design,anti-seismic structural measures and construction technology of modern rammed earth construction are introduced in detail,which can provide reference for future engineering practice.